The heptadentate Schiff baseligand, 2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazoline (H333api), yields [Ln2api2] species when combined with lanthanide salts under basic conditions. A survey of the magnetic properties of this dinuclear lanthanide motif (Ln = Gd, Tb, Dy, Ho) has identified weak magnetic exchange, antiferromagnetic in nature for the isotropic gadolinium analogue, while single molecule magnetic behaviour is displayed in the case of the anisotropic dysprosium complex.